Design Of Powertrain And Control Scheme Of Plug-in Hybrid Passenger Car

With the increasing of car numbers in China,the fossil fuel consumption and exhaust gas emission becoming more and more serious,to solve these problems,the plug-in hybrid electric vehicle(PHEV)is just appeared and received widespread attention by governments and vehicle manufacturer for solving the problems of energy consumption and environmental pollution.PHEV has the advantages of pure electric vehicles and hybrid vehicles,i.e.long continued mileage,low fuel consumption,less emission of exhaust pollutants.The energy saving effect and mileage of PHEV are decided by two aspects: One is the matching design of PHEV power system,the other is the control scheme design of engine and motor working mode.These are the critical engineering technical problems for the PHEV design.According to this,the research goal is to ensure the power and fuel economy of PHEV,the powertrain technical scheme is put forward and analyzed for the PHEV,and,finally,the technical scheme of industrialization of PHEV for Dongfeng Motor Corporation is formed.The research contents are as follows:(1)On the basis of strong-hybrid-technology and Dongfeng Motor Corporation’s own resources,a powertrain scheme,that suitable for engineering development,is proposed to improve,rematch design power assembly of PHEV.The power system adopts a hybrid structure,engine and dual motor are the power sources.The power requirements of the motor is determined by the NEDC working condition,and then the performance parameters of engine,motor,coupler is confirmed according to the maximum vehicle speed,acceleration capability,climbing ability.The battery pack is chosen according to the motor power and mileage requirement.Then,on the basis of maximum climbing ability and minimum steady vehicle speed,the transmission ratio of the coupling system is determined.The feasibility analysis of power system(including engine,batteries,transmission system,motors)arrangement is analyzed,the design boundary and volume requirements are proposed.(2)According to the urban operating conditions of passenger vehicles,the seven operating modes of power system is proposed.On the basis of vehicle operating conditions and battery energy status,the accurately control working modes of the engine and the dual motor is realized,which meets the vehicle power demand and at the same time gets maximum fuel economy.With the help of dual motors working with the engine,the engine always operates in the best efficiency area.The control scheme of PHEV powertrain for Dongfeng passenger car is obtained with the designing principle that generalization and platform.Adopting the algorithms such as interpretation of driver intentions,energy allocation of powertrain system and control torque actuator,the vehicle performance(power and economy)of PHEV is optimized.(3)On the basis of D2P-toolkit Motohawk,the program software of control strategy of power assembly of PHEV is developed,the test-bed of power system is established,the trial manufacture and road test is conducted,and the power and economy of the whole vehicle is experimental investigated.According to the experimental results,the problems of electromechanical coupler and fuel economy of vehicle are found,and the structure has been redesigned,finally,the design requirements have been met and the vehicle development of PHEV is achieved.